Coupler
Couplers, AlsoKnownAs Couplings are mechanical assemblies that join railcars so to makeup a trains consist. The couplers, track gage, brakes, clearances, etc of a given railcar, are just some of many factors that determine compatibility with other pieces of rollingstock & a specific railway. An entire Coupler assembly, AlsoKnownAs draftgear, typically includes various components: drawbar, yoke, cushioning,... There are 3 very general categories of couplers: * FullManual Couplers require a man stepping in between cars to manually couple+decouple mechanical + pneumatic + electric connections. * SemiAuto Couplers automaticly couple+decouple the mechanical connection, but still require manual pneumatic + electric connections. * FullAuto Couplers automaticly couple+decouple all mechanical + pneumatic + electric connections. Link&Pin Couplers This coupler is a FullManual design that originated on NAmerican railways in the early 1800s. The Link&Pin coupler is cheap to make & simple yet dangerous to use. A drawbar\buffer projecting away from the frame allows access to a vertical pin that holds a link in place. The link extends out the end of the drawbar\buffer. As railcars come together, the opposite pin is raised by hand, the link guided into the opposite drawbar\buffer, then the 2nd pin is lowered, thus joining the cars. Uncoupling is accomplished by performing the same procedure in reverse. Link&Pin Couplers have caused many injuries\deaths, & the loose links &\or pins were often stolen, rendering the coupler useless. This design was outlawed by the US Congress beginning in 1893 & the Janney\AAR coupler became standard in NorthAmerica. Link&Pin Couplers have been generally outlawed worldwide & now are only found on historic\museum rollingstock & isolated colonial\narrowgage lines or on industrial\plant stock. 3Link Couplers This coupler is a FullManual design that originated on British railways in the early 1800s, & yet just recently have been removed from service with the retirement of legacy BritishRailways\BR LooseCoupled Goods\Freight stock. The 3Link Coupler is cheap to make & simple yet dangerous to use. Stock fitted with this coupler have a drawhook connecting to internal draftgear, along with a pair of sprung buffers on each end of the car. A 3Link chain hangs from a gedge\notch in each hook shank; after 2 cars are pushed together, one of the two 3Link chains is lifted into the opposing hook. A shunting pole can be used to manipulate the chains, which is somewhat safer than being between the buffers. A disadvantage of this design is the resulting "loose" coupling, meaning several inches of slack is inherent, which must be taken up in tension as the consist accelerates & again compressed as the consist decelerates. This causes much wear & tear on each cars structure, draftgear, buffers & lading, thus as improved coupler designs became available, only slow goods\freight stock were allowed to use 3Link Couplers. An advantage is less of the consists weight is on the locomotive as it accelerates, thus why this coupler remained is use so long. The legacy BR 3Link Coupler is compatible with legacy BR Instanter Couplers & standard BR\EU\UIC Screw Couplers. Instanter Couplers This coupler is a FullManual design. AlsoKnownAs Close Couplers, this coupler is a mechanical improvement over 3Link Couplers; the 3Link standard center link is now replaced with a special triangular link, allowing 2 positions: LooseCoupled or CloseCoupled. LooseCoupling is used during shunting; CloseCoupling is used running in trains; a shunting pole can be used to connect\disconnect\adjust the Instanter chain. Screw Couplers This coupler is a FullManual design, & has become standard on British +Irish +European rollingstock, both in Goods\Freight & Passenger service. Screw Couplers are a mechanical improvement over 3Link & Instanter Couplers; in essence this is a 3Link with an opposingthread turnbuckle replacing the chains center link. However this designs operation is more dangerous, as a shunting pole can not be used; a trainman must go between cars & buffers to connect\disconnect this coupler. Standard BR\EU\UIC Screw Couplers are compatible with legacy BR 3Link +Instanter couplers. Janney Couplers : Janney\AAR\ARA\MCB couplers are a SemiAuto design: mechanical mating+separation is automatic with any required PneumaticPipe+ElectricCircuit connection being seperate & manual. Inspired by the human hand then patented 1873~1914 by E.Janney Of USVI, the design was steadily tested+improved thru many decades by the McConway&TorleyCo, PennsylvaniaRailRoad\PRR, MasterCarBuilders\MCB, AmericanRailwayAssoc\ARA, AmericanAssocRailways\AAR & AmericanPassengerTransitAssoc\APTA to become a practical proven coupler, that requires little or no maintenance, reliable & consistent in abusive services & extreme environments. : Janney couplers operate much like Willison couplers, but with jointed\hinged nuckles instead of interlocking heads. At least one nuckle must be open to allow mating; as 2 cars come together, the nuckles are pushed closed by the palm of the opposing coupler until latch pins hold the nuckles locked. To decouple, cars are pushed together for slack, one pin is raised with a side lever allowing that nuckle to open & the cars are free to part. An advantage over Willison couplers is Janney couplers intentionally have nuckles of lower strength than the body or shank, thus acting as ShearPins if overstressed; a broken nuckle is readily replaced onsite by the train crew; a disadvantage is Willison couplers mate without concern for nuckle closed\open position. : Janney\AARC\MCB5 standard couplers was made law by the US Congress in 1893, forcing the replacement of dangerous Link&Pin couplers on Freight stock & unreliable MillerHookPlatform couplers on Passenger stock, greatly reducing injuries & allowing efficient interchange of rollingstock amongst 4f708 1m435 StandardGage railroads throughout NAmerica. : Janney\AARE couplers, superceding AARD\ARAD +AARC\MCB5, became the AARE standard in 1932 for general Freight Wagons: BoxCars+CenterBeams+Hoppers+Flats+Gondolas+InterModals+AutoRacks+Reefers... The AARE is compatible with other AAR\ARA\MCB\Janneys, & is most common of all AAR coupler types. : Janney\AARF\InterLock couplers, conceived in 1901 by E.Ramsay@PrattCoalCo of USAL, became the AARF standard in 1954 for RotaryGondola+ChemicalTank Freight Wagons & later for general service Lokomotives. The AARF is compatible with other AAR\ARA\MCB\Janneys, prevents decoupling\telescoping\punctures in a derailment, minimizes slack, & allows RotaryDumping of Gondola Freight Wagons. : Janney\AARH\TightLock couplers originated in 1915~1927 Atlas designs by E.Henricot of Etienne Belgium, manufactured for NMBS\SNCB Passenger Stock, as improvement over ARAD+Alliance couplers of that era. A further improved & noticably evolved design, first used 1928 in America on the NewYorkCentralRailRoad, became the AARH standard in 1947 for Passenger Wagons+MultipleUnits. The AARH is compatible with other AAR\ARA\MCB\Janneys, prevents decoupling\telescoping\punctures in a derailment, minimizes slack, & allows PneumaticPipe+ElectricCircuit appliances that convert AARH couplers from SemiAuto to FullAuto operation. : Beyond NAmerica, Janneys were slow to be accepted, having to overcome legacy standards & local politics; after 100+ years of a chaotic mix of colonial couplers, Janney\Sharon\Alliance\SASKop couplers have gradually become common on Passenger +Freight\Goods stock in Australia +Burma +China +India +Indonesia +Japan +Korea +Malaysia +NewZea +Saudi +SAfrica +Thai +Vietnam +... : Janney\DropHead\SwingHead couplers, which pivot to a standard BR\EU\UIC Screw coupler hook, along with Janney\Alliance\Henricot couplers are used on some Passenger +Freight\Goods unit trains in Britain & Europe. : Willison Couplers Willisons are SemiAuto couplers originating in 1913 designs by J.Willison@NationalCastingsCo\NaCo of USOH. First intended for abusive duty in extreme environments, the rugid Willison Coupler has become a worldwide standard for farm\plantation, mine\industrial, & colonial\narrowgage railways, in 0.50Scale +0.75Scale +FullScale sizes. Willison Couplers operate much like Janney Couplers, though with interlocking heads instead of hinged nuckles. A Willison advantage compared to Janneys, is they mate without concern for nuckle closed\open position; a disadvantage is the Willison does not have breakaway\replaceable nuckles & head\shank failures are not repairable onsite by the train crew. After the original design was enlarged\improved by NaCo+LAFLoyd, combination Willison+Screw Couplers were used on 1932~1970 French\SNCF.141TC locomotives & associated passenger cars serving Paris~Nord routes. After further testing\improvement, in 1935 Russia made the Willison\CA3 coupler standard for the entire RZD broadgage railway; this version has cast letters CA3 meaning CоветскихAвто3 in Russian or SA3 meaning SovietAuto3 in English, & is used across continental Russia +FinLand +Mongolia +Ukraine +Turkey +Iran... A newer CоветскихAвтоKuppling5\CAK5\CAKv version is used in Russ~Euro interchange, being compatible with both Russian\RZD CA3 & BR\EU\UIC Screw Couplers. Scharfenberg Couplers Scharfenbergs are FullAuto couplers originating in 1903 designs by K.Scharfenberg of Konigsberg Germany. AlsoKnownAs SchaKu\Dellner\Voith couplers, Scharfenbergs have become the most common coupler worldwide to be used on unit passenger trains: DMUs +EMUs +Tram\LRVs... As two Scharfenberg couplers come together, brakepipes mate & cocks automaticly open, & rotating covers reveal electric contacts. To uncouple, a remote release is operated from the cab. Evolutions of the Scharfenberg, Shibata & Shinkansen couplers are standard on Japanese +Korean passenger stock. The higher cost, relative complexity, need for covers\heaters in dirty\winter service, & limited draft ratings, has prevented this coupler from being commonly used on freight\goods stock. References * RailCarCouplers At OBTS Wiki * RailCarCouplers At WikiPedia * Book: The Railway Data File. Published 2000 by Silverdale Books Category:Locomotive Parts Category:Steam Locomotive Principles Category:Diesel Locomotive Principles Category:Electric Train Principles Category:Encyclopedic articles